1. Faculty of Physics, University of Białystok, Lipowa 41, 15-424 Białystok, Poland
2. The Andrzej Sołtan Institute for Nuclear Studies, 05-400 Swierk/Otwock, Poland
3. Department of Physics, Technical University of Radom, Malczewskiego 29, Radom 26-600, Poland
4. Institute of Atomic Energy, 05-400 Otwock-Świerk, Poland